Windows x64: Cannot use inline assembly.

(transplanted from 0b621f8a1ee707527325eb70e59ef02c63e2bd10)

indra/llmath/llmath.h

@@ -153,7 +153,7 @@ inline F64 llabs(const F64 a)
 
 inline S32 lltrunc( F32 f )
 {
-#if LL_WINDOWS && !defined( __INTEL_COMPILER )
+#if LL_WINDOWS && !defined( __INTEL_COMPILER ) && !defined( _M_AMD64 )
 		// Avoids changing the floating point control word.
 		// Add or subtract 0.5 - epsilon and then round
 		const static U32 zpfp[] = { 0xBEFFFFFF, 0x3EFFFFFF };
@@ -179,7 +179,7 @@ inline S32 lltrunc( F64 f )
 
 inline S32 llfloor( F32 f )
 {
-#if LL_WINDOWS && !defined( __INTEL_COMPILER )
+#if LL_WINDOWS && !defined( __INTEL_COMPILER ) && !defined( _M_AMD64 )
 		// Avoids changing the floating point control word.
 		// Accurate (unlike Stereopsis version) for all values between S32_MIN and S32_MAX and slightly faster than Stereopsis version.
 		// Add -(0.5 - epsilon) and then round